This application claims the priority of International application No. PCT/EP01/08454 filed Jul. 21, 2001, and German Patent Document No. 101 12 424.4 filed Mar. 15, 2001, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a front part of a motor vehicle having a fender unit.
German Patent Document No. DE 38 25 071 C1 has already disclosed a front part of a motor vehicle with a fender unit which is connected to a bottom supporting structure of the motor vehicle and in which cooling air openings are made in a fender covering in order to supply cooling air to the drive assemblies arranged behind the fender unit. The cooling air openings are arranged above and below a transverse carrier which is associated with the fender unit and into which a fender which is elastic with respect to impacts is integrated.
In order to pass on the air flowing through the cooling air openings to the drive assemblies with as few flow losses as possible, an air guiding part, which forms an air guiding duct, is arranged between the fender covering and the bottom supporting structure.
With such or similar additional assemblies for improving the efficiency of the drive assemblies in the front region of a motor vehicle, the packing density is increased more and more so that there is less structural free space for the configuration of measures to improve pedestrian protection in the event of collisions.
The invention is therefore based on the object of developing a front part of a motor vehicle of the generic type to the effect that, while maintaining the advantageous effect of the air guiding part, protection of pedestrians in the event of a collision is improved.
By reinforcing the fender covering with a component which is already present, such as the air guiding part, the structural space which is available in the front of the motor vehicle for improving the impact protection for pedestrians is utilized to an optimum degree. Here, the air guiding part has a reinforcing effect on the fender covering in a region positioned in front of the fender so that in the event of a collision a pedestrian firstly enters into contact with this region which runs approximately at the level of the pedestrian's lower legs. The movement impetus which acts in the lower leg region away from the front part of the motor vehicle causes the pedestrian to be slung around about the center of gravity of his body so that his upper body moves in the direction of the engine hood. In the process, the fender which is of resilient construction is pressed in so that the pedestrian rolls across the engine hood in a defined fashion. At the same time, the reinforcement of the fender covering acts as an under-ride protection for pedestrians so that they cannot be pulled under the motor vehicle in the event of a collision. The air guiding part is set here in such a way that the necessary supporting force is reached quickly and maintained while the acceleration values and the necessary penetration paths for the pedestrian are preserved.
As the air guiding part extends over virtually the entire width of a motor vehicle, the fender covering is also reinforced in the lateral regions of the front part of the motor vehicle, and at the same time the cross-sectional surface which is available in the front area of the motor vehicle is used to an optimum degree for feeding cooling air.
In one preferred embodiment, the air guiding part is supported at the front end by two longitudinal carrier sections which are associated with the bottom supporting structure. The air guiding part is embodied as an injection-molded part, and the plastic used should be relatively rigid, impact-resistant and not too brittle. The connection to the front ends of the longitudinal carrier sections permits stable support on already existing components which can be integrated into the injection-molded part without much additional expenditure on change.
A rear end collision protection element which is fitted over the front ends of the longitudinal carrier sections acts, in addition to its function as a support of the air guiding part, as a rear end collision protection in the event of minor damage. For example, when the rear end of the motor vehicle strikes against curves or the like, the longitudinal carrier sections which are associated with the supporting structure can be protected to an optimum degree against damage by the rear end collision protection element. The rear end collision protection element is preferably manufactured from plastic so that adaptation to virtually any shape of the connection between the supporting structure and the air guiding part can be brought about.
In order to reduce the manufacturing costs further, the air guiding part can be constructed as one piece with the rear end collision protection element.
As a result of the air guiding part extending laterally beyond the supporting points on the front ends of the longitudinal carrier sections, the pedestrian protection is also provided even when there is an offset collision with a pedestrian.
In order to support the air guiding part uniformly on the fender covering, the contour of the air guiding part which faces the fender covering is adapted to the internal contour of the fender covering. In addition, the fender covering can be prestressed by the air guiding part in order to improve the dimensional stability of the fender covering.
In one particularly preferred embodiment, the air guiding part has a wing-like shape. In order to make the air guiding part inherently stable, a number of reinforcement ribs which are oriented in the longitudinal direction of the motor vehicle and which are spaced apart from one another in the transverse direction of the motor vehicle are arranged on the upper side of the wing.
Reinforcement ribs which extend from the underside of the wing in the direction of the fender covering act in a particularly reinforcing fashion in the lower region of the fender covering. The matching of the terminating edge of each reinforcement rib to the internal contour of the fender covering particularly increases the degree of rigidity in this region so that in the event of a crash the lower limb of a pedestrian can bounce off.
The formation of an at least partially closed hollow section by the covering, the fender, and the air guiding part provides further reinforcement in order to protect pedestrians against impacts with simple means. Here, the wing can be attached by its terminating edges to the fender covering, or else only bear against it.
In addition to supporting the air guiding part on both sides on the front ends of the longitudinal carrier sections it is possible to provide support on a transverse carrier which connects the front longitudinal carrier sections. This further improves the degree of rigidity of the fender covering in the lower region.